In calcining various solid materials, for example, dolomite lime, the off gas from the calcining operation carried significant amounts of fine particulate materials which must be removed from the gas stream before emission of the gas stream to the atmosphere to comply with environmental regulations.
To accomplish this objective, various filter devices have been provided to electrostatically or mechanically remove the particulate matter. One problem encountered in the removal of particulate material susceptible to cross crystallization by mechanical means for example, by passing the gas stream through selected media, is the propensity of certain inorganic materials such as lime or dolomitic lime to co-react in the presence of certain promotors to cause separate particles to adhere to each other, so that the particulate material agglomerates or combines in the presence of such cross crystallizing agents, such as water and carbon dioxide, with the formation of extremely large particles which are retained in the media thereby adversely effecting the efficiency of the filter media.
Additionally, the presence of cross crystallizing agents promotes growth of deposits of particulate material on the media surface leading to blinding of the supporting screens by the hard deposits with resulting permanent loss of efficiency in cleaning.
Presently, no satisfactory means are known for prevention of cross crystallization and the attendant problems in connection with the removal of certain particulate material from a gaseous stream.